Java streams: merge/map collections

Question

I've this class:

private class Item {
  private String transactionId;
  private String user;
  private LocalDate expiration;
  private String confidential;
  private String locked;
}

By other hand, I've five collections:

List<String> transactions;
List<String> users;
List<LocalDate> expirations;
List<String> confidential;
List<String> lockeds;

So I need to map each n of each collection to a new Item object.

Any ideas?

Eran · Accepted Answer · 2018-10-16 09:02:15Z

10

Stream over the indices (assuming all 5 lists have the same number of elements):

List<Item> items = IntStream.range(0,transactions.size())
                            .mapToObj(i -> new Item(transactions.get(i),
                                                    users.get(i),
                                                    expirations.get(i),
                                                    confidential.get(i),
                                                    lockeds.get(i)))
                            .collect(Collectors.toList());

edited Oct 16, 2018 at 9:02

answered Oct 16, 2018 at 8:52

Eran

395k57 gold badges726 silver badges793 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Jordi Over a year ago

It's telling me that IntStream.map has to return an integer... cannot convert from Item to int

Eran Over a year ago

@Jordi oops. you're right. I'll fix it. It should be mapToObj

Jordi Over a year ago

Only one more question... Could I create anonimous type?

Eran Over a year ago

@Jordi what do you mean? What would that anonymous type implement/extend?

Jordi Over a year ago

I mean, if it's possible to create a "dynamic" map object without declaring any class, or declaring it on the fly inside mapToObj

Collectives™ on Stack Overflow

Java streams: merge/map collections

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related